1. Field of the Invention
The present invention relates to novel useful intermediates for producing optically active cyclic amino acids (for example, optically active proline, pipecolic acid, etc.), which are useful for producing pharmaceuticals, agrochemicals and the like, and to processes for producing and using the same.
2. Description of Related Art
Heretofore, a process has been known as processes for producing racemic proline and pipecolic acid, in which process pyrrolecarboxylic acid or pyridinecarboxylic acid is hydrogenated [Journal of Organic Chemistry, 1990, 55, 738].
Although processes in which racemic proline or pipecolic acid is optically resolved with tartaric acid have been known [Bulletin Chemical Society of Japan, 64, 3251 (1991)], such processes have a problem in separation of proline or pipecolic acid from the resolving agents.
Processes also have been known in which proline or pipecolic acid is first converted into N-(benzyloxycarbonyl)proline or N-(benzyloxycarbonyl)pipecolic acid, which is then subjected to optical resolution with optically active tyrosine hydrazide, and then a hydrogenolysis [Monatshefte fur Chemie 101, 1177 (1970)], but such processes have drawbacks in that they require expensive and not readily available resolving agent in an industrial scale.
As a process for producing optically active pipecolic acid, a process also has been known in which process optically active lysine is used [Chem. Pharm. Bull., 24, 621 (1976), Japanese unexamined patent publication No. Hei 2-229152], but it is not always satisfactory in an optical purity.